This invention relates generally to inflatable restraint systems and, more particularly, to improved treatment of the emission of an inflator of such inflatable restraint systems.
It is well known to protect a vehicle occupant by means of safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., “passive restraint systems.” Such systems commonly contain or include an inflatable vehicle occupant restraint or element, such as in the form of a cushion or bag, commonly referred to as an “airbag cushion.” In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such airbag cushions may desirably deploy into one or more locations within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, instrument panel or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior. For example, typical or customary vehicular airbag cushion installation locations have included the steering wheel, the dashboard on the passenger side of a vehicle, along the roof line of a vehicle such as above a vehicle door, and the vehicle seat such as in the case of a seat-mounted airbag cushion. Other airbag cushions such as in the form of knee bolsters and overhead airbags also operate to protect other or particular various parts of the body from collision.
In addition to an airbag cushion, inflatable passive restraint system installations also typically include a gas generator, also commonly referred to as an “inflator.” Upon actuation, such inflator devices desirably serve to provide an inflation fluid, typically in the form of a gas, used to inflate an associated airbag cushion.
Various types or forms of inflator assemblies or devices have been disclosed in the art for use in inflating an airbag cushion such as used in inflatable restraint systems. One type of known inflator device derives inflation gas from a combustible solid pyrotechnic gas generating material which, upon ignition, generates a quantity of gas sufficient to inflate the airbag.
In such and similar inflator devices, the reaction or burning of solid gas generant and/or initiation materials almost invariably results in the production or formation of a gaseous product having an elevated temperature as well as commonly containing elevated levels of particulate materials such as resulting from or remaining after reaction by or of the gas generant and/or initiation materials.
Current state of the art automotive airbag technology typically employs wire filter technology for cooling and filtering the exit gases generated by the reaction or combustion of the gas generating pyrotechnic material contained in such inflator devices. Knitted wire filters are typically cheaper than wire mesh or woven type filters and are widely used in the industry. Such use of knitted wire filters has generally proven as successful at capturing and collecting similar amounts of the solid combustion byproducts entrained in the exit gases produced by the gas generating pyrotechnic and/or initiation materials as other filtration technologies. However, as inflator sizes have been reduced in an effort to satisfy and meet more stringent or sever auto industry weight and size requirements, this type of filtration technology has generally become much less effective at cooling and filtering the exit gases of inflators. More particularly, as the gas paths within inflator system hardware have shortened in length and with less or reduced turning of the gases, such filtration technology has become much less effective at cooling and filtering the exit gases of the inflators.
The results and consequences of such lessened or reduced gas treatment can be significant. For example, gases exiting an inflator device that have higher particulate content and/or higher temperature can necessitate redesign of the system in an effort to avoid and minimize undesired complications such as due to increased module cushion fabric burn through and erosion of the sewn seams due to contact or exposure to such higher particulate content and/or higher temperature exit gases. One possible means to compensate for increased module cushion fabric burn through and erosion of the sewn seams is to redesign the module bags with fabric doublers and seam protection. Such redesigns, however, typically add to the cost, size and/or weight of the module. In addition, wire filters employing smaller wires have been tested but due to the high temperatures of the exiting gases and particulates, such wire filters are prone to be more easily damaged and eroded causing similar problems with module cushion fabric burn through and/or erosion of the sewn seams.
Thus, there is an ongoing challenge to improve the treatment of the gas emission of such inflator devices, particularly in view of weight and size reductions being imposed with modern inflator and passive restraint system design.